Bridging plug with pressure relief means and mandrel latch



y 8, 1969 c. c. BROWN 3,454,089.

BRIDGING PLUG WITH PRESSURE RELIEF MEANS AND MANDREL LATCH Filed Feb 2,1968 Sheet 1 of 4 GIJERO dBROMV /9 IN T R A TTORNEXS July 8, 1969 c. c.BROWN 3,454,089

BRIDGING PLUG WITH PRESSURE RELIEF MEANS AND MANDREL LATCH Filed Feb. 2,1968 Sheet 2' pf 4v ATTORNEYS 7 y: 8, 9' c. BROWN 3,454,089

' BRIDGING PLUG WITH PRESSURE RELIEF MEANS AND MANDREL LATCH Filed Feb.2, 1968' Sheet 3 of 4 I dldA'Ro a. B/POW/V INVENTOR.

A TTORNEXS y 8,1969 BROWN j 3,454,089

BRIDGING PLUG WITH PRESSURE RELIEF MEANS AND MANDREL LATCH Filed Feb. 2;1968 Sheet 4 of 4 United States Patent 3,454,089 BRIDGING PLUG WITHPRESSURE RELIEF MEANS AND MANDREL LATCH Cicero C. Brown, Brown OilTools, Inc., P.0. Box 19236, Houston, Tex. 77024 Filed Feb. 2, 1968,Ser. No. 702,719 Int. Cl. E21b 33/134, 33/128 US. Cl. 166-128 7 ClaimsABSTRACT OF THE DISCLOSURE Bridging plugs are commonly employed in thepetroleum industry for plugging oil the bore of well pipes, usually theproduction tubing string, for various purposes generally connected withrepair or work-over operations. Some plugs are designed to bepermanently installed, but usually they are of the type which aredesigned to be retrieved when the purpose for which the plug has beeninstalled has been accomplished.

Retrievable type plugs generally employ some form of releasableanchoring device by which the plug may be secured to the well pipe andwhich may then be released to enable the plug to be withdrawn. One ofthe problems encountered with plugs heretofore employed is in holdingthe anchor elements in anchored position under pressure surges andvibrations commonly encountered in operations with which the plugs areemployed. Such surges and vibrations tend to cause release of theanchor-holding elements, causing premature release of the plug withattendant diifiCllltlCS. Also, it is necessary to relieve the fluidpressure usually trapped in the plug in order to balance the pressuresacross the plug to enable the anchor elements to be released, so thatthe plug may be retrieved.

The present invention is directed to improvements in bridging plugs ofthe general type disclosed in my prior Patent No. 2,953,206.

The present invention has for its principal objects the provision of abridging plug design which is compact, relatively simple in constructionand operation; obviates the difficulties encountered with moreconventional designs; and is especially adapted to be run and retrievedwith wire line strings of tools.

A suitable and useful form of bridging plug in accordance with oneembodiment of this invention contemplates a tubular plug body closed atits lower end, and carrying a plurality of radially movable anchor dogsfor anchoring the body to the well pipe in which it is run. Seal meansis mounted about the body above the anchor dogs for sealing between theplug body and the well pipe. A tubular mandrel is slidably disposed inthe plug body for limited reciprocating movements to actuate and releasethe anchor dogs. Fluid circulation passages are provided in the bodyabove and below the seal means, a sleeve valve means is slidablydisposed about the body above the seal means for opening and closing theupper circulation passage to block or permit bypassing of fluid aroundthe seal means. A latch means, operated by cooperating axial movementsof the mandrel and sleeve valve means, is provided to secure the mandrelin the down or inward position in the body to hold the anchor elementsin anchoring position and to thereafter release the same. The mandrelsleeve valve means are actuated in effecting the plug setting andreleasing movements by means of Wire line suspended tools.

Various other objects and advantages of this invention will become morereadily apparent from the following detailed description when read inconjunction with the accompanying drawing which illustrates one usefulembodiment in accordance with this invention.

In the drawing:

FIG. 1 isa longitudinal, partly sectional view of the bridging plugshowing the parts in the positions occupied when being run into pipestring, the plug being shown carried in on a setting tool;

FIG. 2 is a view similar to FIG. 1 showing the parts in anchored or setposition;

FIG. 3 is a view similar to FIG. 2, showing the setting tool beingwithdrawn after release from the plug;

FIG. 4 is a view similar to FIG. 2 showing a wire lineoperated overshotconnected to the plug preparatory to effecting its release;

FIG. 5 is a view similar to FIG. 4, showing the plug in releasedcondition, the parts thereof being returned to the positions initiallyoccupied in FIG. 1;

FIGS. 6 and 7 are cross-sectional views taken, respectively, along lines6-6 and 7-7 of FIG. 1;

FIG. 8 is a cross-sectional view taken along line 88 of FIG. 2;

FIG. 9 is a cross-sectional view taken along line 9--9 of FIG. 3; and

FIG. 10 is a cross-sectional view taken along line 10- 10 of FIG. 5.

A setting nipple 10 having a central bore 11 is adapted to be installedin and to form a part of a tubing string (not shown) into which thebridging plug is to be run. The nipple is provided at a pointintermediate its ends with an annular recess 14 having upwardly anddownwardly bevelled upper and lower end walls 15 and 16, respectively,defining longitudinally spaced, inclined shoulders. The bore wall ofnipple 10 is also provided with an internal shoulder 17 spaced slightlybelow the lower end of recess 14.

The plugging device proper comprises the generally tubular body 18closed at its lower end by a cap 19 threadedly secured at 20 to thelower end of body 18 and provided with a conical guide nose 21.Intermediate its ends, body 18 is provided with a plurality of angularlyspaced radial openings 22, in each of which is mounted a radiallymovable anchor slip or dog 23, each having a pair of longitudinallyspaced, inwardly projecting lugs 23a- 23a which define between them arecess 19a. The inner and outer edges at the upper and lower ends of thedogs are bevelled at 26 and 27, respectively. The portion of body 18just above openings 22 is reduced in external diameter at 28 to providethe upwardly facing shoulder 28a. A series of ring packings 29,preferably of the chevron or other pressure sealing type, are positionedabout reduced portion 28 and are compressed against shoulder 28a bymeans of a sleeve nut 30 which is threaded onto the reduced diameterportion 28. The portion of body 18 above sleeve nut 30* is furtherreduced in two steps at 3011 and 301), the juncture of which is definedby an upwardly facing external shoulder 31. The portion of body 18 belowopenings 22 is reduced slightly in diameter to form a downwardly facing,inclined shoulder 32 adapted to abut shoulder 17 and to thereby positiondogs 23 opposite recess 14 when the plug body is fully inserted into theseating nipple. A plurality of radial ports 33 are provided through thewall of body 18 between shoulder 32 and the lower end of the body toprovide communication between the interior of body 18 and the exteriorthereof through the space between the wall of nipple and the exterior ofcap 19. The upper end portion of body 18 has its bore somewhat reducedin diameter thereby thickening the wall thereof to form a latching headhaving a plurality of radial openings 36 therein, in which are mounteddetents or ball latches 37 for movement radially inwardly and outwardlyof openings 36 in a manner and for purposes to be described more fullyhereinafter. Ball latches 37 will have a diameter somewhat greater thanthe thickness of latching head 35. Immediately below the enlargementforming latching head 35, body section 30b is provided with a pluralityof radial by-pass ports 38 which communicate the bore of body 18 withthe exterior thereof.

Slidably disposed about body portion 30b is a sleeve valve 40 carryingon its inner wall a pair of longitudinally spaced annular seals 41 whichare positioned to be below ports 38 when the sleeve valve is in itslowermost position abutting shoulder 31, and when moved to an upperposition, as will be described subsequently, will be disposed above andbelow ports 38 to effectively close off fluid communication through thelatter. Above seals 41, sleeve valve 40 is provided with a plurality ofradial ports 42 which are positioned to be in substantial register withports 38 when the valve is in the down or open position, as seen inFIG. 1. The internal diameter of sleeve valve 40 is such that when movedto its upper position it will urge ball latches 37 inwardly and functionas a keeper for the latter, as will appear subsequently. Above ports 42sleeve valve 40 is reduced in internal and external diameter to providethe annular neck 43 which defines an upwardly facing shoulder 44 aboutthe exterior of the neck and an upwardly facing internal shoulder 44ainteriorly of the neck. An abutment ring 45 is seated in the exterior oflatch head 35 above openings 36 and is adapted to engage shoulder 44ainresponse to longitudinal movement of sleeve valve 40 upwardly relativeto latch head 35, to thereby limit the upward movement of valve 40 to aposition closing off by-pass ports 38 and thrusting ball latches 37inwardly.

A coil spring 46 surrounds body section 30a in compression betweensleeve nut 30 and the lower end of sleeve valve 40 tending toresiliently bias the latter upwardly relative to body 18, for purposeswhich will appear subsequently.

Coaxially disposed for sliding movement in the bore of body 18 is agenerally tubular mandrel 50 which extends upwardly out of the upper endof body 18. Adjacent its lower portion mandrel 50 has formed thereon apair of longitudinally spaced, radially enlarged expander lugs 5151, thespace '52 between the lugs being such that the lugs will be inregistration with lugs 23a when mandrel 50 has been moved downwardlyrelative to body 18, as will appear subsequently. The bore of body 18,just above Openings 22, is radially enlarged to form the recess 53 toreceive the upper one of the lugs 51 in the course of operation of thedevice, as will be described hereinafter.

At a point spaced a short distance below its upper end mandrel 50* isprovided with an annular latching recess 54 positioned to be moved intoand out of registration with openings 36 in the plug body in the courseof operation of the device. Adjacent its lower end mandrel 50 isprovided with a plurality of radial ports 55 which, in the unsetposition of the plug as shown in FIG. 1, will be located at a pointabove seal packing 56 mounted in the wall of cap 19, and in the setposition of the plug will be below packing '56, as seen in FIG. 2. Inthe position shown in FIG. 1, port '55 will be in communication withports 33 in the plug body and thereby communicate the bore of themandrel with the exterior of the plug and when below seal packing 56will close off this communication. At a point above recess 54, themandrel is also provided with a plurality of radial ports 57 whichcommunicate the bore of the mandrel with the exterior of the plugstructure above the upper end of body 18. Ports 55 and 57, as well asports 33 and 38 in the plug body, function as circulation ports throughwhich fluids will be displaced when the plug is being lowered into awell pipe. The upper end of mandrel 50 is externally threaded forinsertion into the externally threaded socket 60 of a fishing head 61which carries at its upper end an enlargement 62 having its upper endface formed as an upwardly tapering conical surface 63 and defining anundercut annular shoulder 64.

The plug structure is run, or carried, into setting nipple 10 on asetting sleeve 65 having an annular skirt 66 at its lower end, the wallthickness of which is such that it fits snugly about neck 43 of thesleeve valve and seats against shoulder 44. A shear pin 67 is disposedbetween the exterior of neck 43 and skirt 66 to initially secure thesetting sleeve to sleeve valve 40. The intermediate portion of settingsleeve 65, above skirt 66, is reduced in internal diameter to define thebore 68 which is adapted to have a close sliding fit over socket 60' andenlargement 62 of the fishing head. A second shear pin 69 is mountedbetween the exterior of socket '60 and the wall of bore 68 of thesetting sleeve to thereby secure the setting sleeve to the mandrel. Thelongitudinal spacing between shear pins 67 and 69 is selected to be suchthat when the setting sleeve is secured to the mandrel through shear pin69, the lower end of skirt 66 of the setting sleeve will have pushedsleeve valve 40 to its lower or open position, compressing spring 46, asbest seen in FIG. 1. The upper end of setting sleeve 65 is formed withan axial opening 70 which is smaller in diameter than bore 68 of thesetting sleeve and thereby defines the downwardly facing internalshoulder 71. A hanger member comprises a shank 72 which extends slidablythrough opening 70 and carries an enlarged head 74 on its lower end tobear against shoulder 71. The hanger member forms the means by which theplug and setting sleeve are carried into the well and operated therein.The lower face of head 74 has a conical reentrant surface 75complementing the upper surface 63 of fishing head 62. The upper end ofshank 72 is threadedly secured to the lower end 76 of a conventionalstring of wire line tools, indicated at S, generally including a set ofconventional wire line jars (not shown), by which not only may the plugbe run into pipe string 10 but by means of which upwardly and downwardlydirected jarring blows may be applied to these several parts of the plugstructure, as will be described hereinafter.

In operation, the plug, connected to setting sleeve 65 and the wire linetool string S with the parts in the relative positions shown in FIG. 1,will be run through the pipe string into setting nipple 10. As shown inFIG. 1, the connections formed by shear pins 67 and 69 between thesetting sleeve and the plug body and mandrel, respectively, willposition mandrel lugs 5151 in interspersed relation with upper lugs 23aof the anchor dogs. In this position, it will be seen that dogs 23 arefree to move inwardly of openings 22, so as to allow the plug to movefreely through bore 11 of the pipe string until shoulder 32, on thelower end of body 18, engages shoulder 17 of the setting nipple,stopping the plug with dogs 23 opposite recess 14 in the setting nipple.When this position has been attained a downward jar is applied throughtool string S against the upper end of fishing head 62, sufiicient forcebeing applied to break shear pin 69 and drive mandrel 50 downwardly inthe bore of plug body 18. This downward movement will cause the bevelledfaces of mandrel lugs 51 to engage the corresponding faces on lugs 23aof the anchor dogs, causing the latter to be pushed outwardly intorecess 14 and allowing the mandrel lugs to move downwardly intoregistration with lugs 23a, as shown in FIG. 2. Movement to thisregistering position will be timed by the engagement of the lower end ofmandrel 50 with the shoulder formed by the angular shape defining theinner wall of nose 21.

It will be understood that before the mandrel is moved downwardly andwhile the tool string is moving downwardly through setting nipple 10,any fluid in the pipe string will be free to move through ports 33 and55 and thence through the bore of mandrel 50 out of ports 57, and thencebetween mandrel 50 and skirt 66, passing out of the plug body throughports 42. Also, fluid entering ports 33 will be displaced upwardlythrough the annular space bet-Ween mandrel 50 and body 18, bypassingseal packing 29, and will exit out of bypass ports 38 and thence throughports 42 to the exterior of the plug, being so-directed by the sealformed by packing 35a which seals between latching head 35 and mandrel50 at a point above ports 38. In this way, the plug structure may movefreely through the bore of the pipe string and setting nipple to itssetting position.

When the mandrel has been driven downwardly to the position moving dogs23 into anchoring position in recess 14, as previously described,latching recess 54 in the exterior of the mandrel will have movedopposite openings 36, thereby allowing ball latches 37 to move inwardlyinto recess 54. At the same time, by reason of the release of shear pin69, the tool string may be picked up, raising setting sleeve 65 togetherwith sleeve valve 40' which remains secured thereto, carrying the sleevevalve to its upper position shown in FIG. 2, at which not only iscirculation cut off through bypass ports 38 and 42, but also moving thesleeve valve to a position behind ball latches 37, so as to effectivelyhold the latter in latching engagement in recess 54 and therebyeffectively lock mandrel 50 in its downward position holding anchor dogs23 locked into recess 14.

With anchor dogs 23 thus locked into anchor recess 14, an upward pullmay now be applied through tool string S which will first lift head 74of the hanger into engagement with shoulder 71 of the setting sleeve andthereafter will apply upwardly directed force sufiicient to break shearpin 67, and thereby release the setting sleeve from a sleeve valve 40and thus from the plug structure as a. whole, as best seen in FIG. 3.The setting sleeve and tool spring may now be withdrawn from the well,leaving the plug in locked position in seating nipple 10, as shown inFIG. 3, with packing 29 sealing off between the plug and the wall ofnipple 10 at a point above the anchor dogs, which will also serve toprotect the latter from any scale or detritus which might otherwisesettle downwardly and interfere with the radial movements of the anchordogs, particularly when it is desired to release the plug member forretrieval from the well. It will be noted that when the setting sleeveis released from sleeve valve 40, as shown in FIG. 3, spring 46 willexpand and will have suflicient strength to hold the sleeve valve in theupper position closing bypass passageways 38. At the same time, bylocking ball latches 37 into latching position in latching recess 54,the plug will be protected against release by reasons of upward surgesfrom below or by vibrations occurring in the course of operation, sincethe latch formed by ball latches 37 and recess 54 can only be releasedby physically pushing sleeve valve 40 downwardly to its lowermostposition and out of engagement with the ball latches.

Reference may now be had to FIGS. 4 and 5 which illustrate theoperations employed in retrieving the plug from the setting nipple andthe pipe string into which it is inserted. To accomplish the retrieval,an overshot tool, designated generally by the letter 0, carried on awire line W, will be run through the bore of the pipe string and willcomprise a tubular skirt 80 having internal and external diametersgenerally similar to that of skirt 66 of the setting sleeve, so that itwill pass over neck 43 of the sleeve valve and bear against shoulder 44.The overshot will be manipulated to apply downward pressure against thesleeve valve to move the latter downwardly against the resistance ofspring 46 with sufficient force to move packings 41 below bypass ports38. This will open communication between the interior of plug body 18and the exterior of the tool, whereby any pressure trapped within theplug body will be relieved to thereby balance any well pressure acrossthe tool so as not to interfere with release of the latter. The overshotcarries in its bore spaced inwardly from skirt 80,

a plurality of resilient catcher fingers 81 which are adapted to beforced outwardly over catcher head 62, and then spring back to engagebeneath shoulder 64.

With the overshot in place, as illustrated in FIG. 4, it will be seenthat the downward displacement of sleeve valve 40 will release balllatches 37 and thereby free mandrel 50 for upward movement under tensionapplied through fingers 81 by pull on wire line W. The upward movementresulting from this operation is illustrated in FIG. 5, wherein it willbe seen that the resulting upward movement of the mandrel has movedmandrel lugs 51 out of engagement with lugs 23a of the anchor dogs,releasing the latter for inward movement out of anchor recess 14. Thelugs 51 will then move upwardly to engage the shoulders 53a which willthen permit the continued upward pull on wire line W to apply upwardlydirected force to the plug body, enabling the whole structure to bewithdrawn and retrieved from the well pipe.

It will be understood that various modifications and alterations may bemade in the details of the illustrative embodiment within the scope ofthe appended claims but without departing from the spirit of thisinvention.

What I claim and desire to secure by Letters Patent is:

1. A bridging plug for closing the bore of a well pipe comprising:

(a) a hollow generally tubular plug body closed at its lower endinsertible in the bore of a well pipe,

(b) radially movable anchor elements mounted in said body projectibletherefrom into anchoring engagement with the wall of the well pipe,

(c) seal means mounted about the body to seal with the pipe wall abovesaid anchor elements,

((1) upper and lower ports in the wall of said body for bypassing fluidaround said seal means,

(e) mandrel means longitudinally movable in the bore of the plug bodyinto and out of projecting engagement with said anchor elements,

(f) cooperating latch elements carried by the body and said mandrellockingly engageable upon movement of the mandrel into projectingengagement with said anchor elements, and

(g) sleeve valve means movably mounted on the body above the seal meansfor movement between positions opening and closing said upper ports,said sleeve valve means being operable when in said port-closingposition to hold said latch elements engaged with said mandrel.

2. A bridging plug according to claim 1 wherein said latch elementsinclude:

(a) an annular recess in the exterior of said mandrel,

and

(b) a plurality of angularly spaced ball latches mounted for radialmovement through the wall of said body into and out of said recess.

3. A bridging plug according to claim 1 including abuttable stopelements carried on the body and sleeve valve means for limitingrelative upward movement of the valve means on said body to saidport-closing position.

4. A bridging plug according to claim 1 including seal packing mountedin the bore of said body to seal between the mandrel and the body at apoint above said upper ports.

5. A bridging plug according to claim 1 including resilient meansmounted about the body to bias said sleeve valve means toward saidport-closing position.

6. A bridging plug according to claim 1 including setting tool meansinitially positioning said sleeve valve means on the body in theport-opening position and releasable after actuation of said anchorelements by said mandrel to'free said valve means for movement to saidport-closing position.

7. A bridging plug according to claim -6 wherein said setting tool meanshas frangible connections both to said mandrel and to said sleeve valvemeans, said connections being spaced to initially hold said mandrelupwardly out of projecting engagement with said anchor elements While 7holding said sleeve valve means in said port-opening position, saidconnections being sequentially releasable first from said mandrel andsecond from said sleeve valve means by manipulation of said settingtool.

References Cited UNITED STATES PATENTS 2,776,015 1/1957 Bielstein 166l338 2,976,931 3/1961 Daifin 166-181 3,180,420 4/1965 Manson et a1. 166-1283,250,331 5/1966 Boyle 166-133 JAMES A. LEPPINK, Primary Examiner.

US. Cl. X.R. 166133, 226

